Rotary casting apparatus



c. POUGNAND 2,917,797

ROTARY CASTING APPARATUS Dec. 22, 1959 Filed Jan. 2, 1957 3 Sheets-Sheet 1 INVENTOR 7 4 ATTORNEYJ Dec. 22, 1959 c. POUGNAND 2,917,797

ROTARY CASTING APPARATUS I Filed Jan. 2, 1957 3 Sheets-Sheet 2 g INVENTOR BY flaw/AW A: 127-4 J4 ATTORNEYS 1959 c. POUGNAND 2,917,797

ROTARY CASTING APPARATUS 3 Sheets-Sheet 3 Filed Jan. 2, 1957 INVENTOR flaw BY Au duo 44., 4 M

46.; ATTORNEY:

United States Patent 2,917,797 ROTARY CASTING APPARATUS Clement Pougnand, Creteil, France, assignor to Normacem Societe Anonyme, Paris, France, a corporation of France I Application January 2, 1957, SerialNo. 632,128 Claims priority, application France September 13, 1956 7 Claims. CI. 22-65) The present invention relates to thenianufacture of metal objects by the casting, in a suitable mold, of metals or alloys in fusion, and is particularly concerned with the casting, from fused non-ferrous metals or alloys, of pieces whose eventual use requires the complete absence of any blisters.

This invention comprises a process and a device for application of the latter.

The process of the present invention consists essentially in melting, in a closed vessel constituted by a crucible the mouth of which is closed by a mold, a small quantity of metal or alloy corresponding to the embodiment of a single object, and casting the metal or alloy in fusion directly into the mold avoiding any entrance of air into the said closed vessel. The fusion is to be effected by any suitable means of heating, in particular by induction means of an electric current of suitable frequency.

Apparatus for usein carrying out this process is characterized by the combination of a crucible of suitable size and material of construction, and a mold for the object, the crucible and mold being so designed and formed formed as to be easily combined in such a way as to form a closed vessel, means being provided to support the said closed vessel and to allow it to assume all useful positions for the purpose of molding; to effect the latter in said closed vessel; to hold the mold and crucible tightly against one another; to tip said vessel at a suitable speed which can be adjusted in such a way as to transfer the molten metal or alloy from the crucible into the mold; and, finally, if necessary, to then cool the assembly to accelerate solidification of the cast metal (or, alloy) in said mold.

As the present invention is particularly adaptedalthough not exclusively so-for the production of objects of cast copper because it provides for effecting the casting in the presence of a limited quantity of air, which may be made small, the invention will, in the following, be described with particular reference to casting, in copper, a squirrel cage for the rotor of a non-synchronous electric motor. This rotor, which is cylindrical, is formed of a stack of insulated magnetic sheets and it has, on its periphery, notches parallel to the axis. The squirrel cage is constituted by bars-formed of copper in this case lodged in these notches, the ends of which bars are connected on either side of the rotor by so-called shunt rings. This embodiment gives rise to several particular dispositions which must be understood as forming a part of the invention. Thus, in the illustrative embodiment the mold is constituted by the rotor itself associated withtwo end pieces which form the said shunt rings. Furthermore, I provide for preheating the mold before casting, so as to facilitate casting-in the channels 'of the mold-molten metal then forming the squirrel cage. Other characteristics will appear in the description in which:

Figs. 1,"2 and 3 represent an embodiment of apparatus according to the invention respectively before fusion, after fusion and before casting, and at the end of a half-turn of rotation;

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Fig. 4 is a longitudinal vertical view taken along section line 4--4, of Fig. 2;

Fig. 5 is a sectional view taken along line 55 of Fig. 1;

Fig. 6 is a longitudinal sectional view of the completed squirrel cage rotor; and

Fig. 7 is a longitudinal sectional view of the molding vessel consisting of the stack of sheets mounted intermediate the end pieces and the crucible.

In these figures, 1 is a stack of sheets forming a rotor, 2 are bars of a squirrel cage, and 3, 3 are shunt rings. The mold is formed by the rotor 1 associated with two end pieces 4 and 5 each comprising a throat in which the corresponding shunt ring is formed. Moreover, the part 4 has openings 6 passing through it from the bottom of said throat to the face opposite that in which this throat is cut.

The crucible is shown at 7. Its volume corresponds substantially to the quantity of copper necessary to produce the desired squirrel cage. It is selected in such a way that very little air remains in the presence of the copper.

In accordance with the invention, the fusion is effected in a closed vessel. This is constituted by the crucible 7, closed by the said mold. As shown in Fig. 1, the crucible is placed on a suitable support and the mold itself is simply placed on the crucible to close it, the openings 6 in the piece 4 opening into the crucible. This assembly is balanced by reason of the fact that the axis of the crucible and that of the rotor are colinear in the vertical direction. This same figure shows, at 8 and 9, windings which when traversed by a suitable electric current serve by induction to heat the mold and, respectively, to pro duce the fusion of the copper in the crucible.

The different means for operating the casting combine the methods of tipping and that of the sling. The organs permitting obtention thereof consist of a machine comprising two parts: a frame sheltering a drive motor (not shown) and a rotating part (Fig. 4).

The rotating part comprises a hollow cylindrical tube 10 provided with two inner partitions 11 and 12 which define three chambers 13, 14 and 15. mobile in chamber 14, and is integral with a shaft 17, which latter passes through partition 12 and into chamber 15 and ends in another piston, 18, in chamber 15. The end of the tube 10 adjacent chamber 15 is open, and is arranged to be covered by a lid 19. The end of the tube 10 adjacent chamber 13 is closed. Inside this chamber 13 a balancing mass 20 can move.

The cylindrical tube 10 is mobile in such a way that its longitudinal axis rotates around its center 0 in a vertical plane. For this purpose it is made integral, for example, by welding, with a plate 21 which is fixed to the end of a tube 22 mounted horizontally in the frame 23 of the machine by means of ball bearings 24. The outer peripheral surface of the plate 21 is provided with grooves (indicated in Fig. 4) in which two V belts, activated by the said motor (not shown), are

engaged. The interior of tube 22 is divided by a concentric tube 31 into two concentric chambers 32 and 25, which, by. means of conduits 32a and 25a provided in the plate 21, communicate with the chamber 14,, each at one end of the latter. On the sideopposite to plate 21, the chambers 32 and 25 communicate with a fixed sleeve 26 which permits connecting each of them to a source of a suitable control agent, water, for example. i

The whole is enclosed in a protective hood or housing 27 having'at the top thereof an opening which can be closed by a lid 28.

Finally, 29 designates a key, of suitable thickness disposed between the piston 18 and the outside base of the A piston 16 is crucible 7, and 30 designates a mass of copper in various stages of its transformation in the crucible.

According to the invention the cast copper squirrel cage is produced as follows:

With the lid 28 open, the tube 10 is prought into vertical position, as in Fig. 1, and the lid 19 is removed. When hydraulic fiuid such as water is forced into chamber 25, the assembly 16, 17, 18 will rise until the piston 18 is in the opening of tube 10. A key 29 is placed on the said piston, then the crucible 7 on the said key. The copper to be melted is piacetl in the crucible which latter is then closed by the mold constituted by the rotor 1 and the two end pieces 4 and 5. The windings 8 and 9, associated with a mobile support (not shown) therefor, are brought around the mold and the crucible, and electric current of selected intensity and frequency passes through these windings for a time determined for each of them. When the melting of the copper is complete, windings 8 and 9 are withdrawn, the supply of fluid to chambers 25 is stopped and the supply of fluid under pressure to chamber 32 is begun. The assembly 16, 17, 18 descends (in tube 10) until piston 18 rests on partition 12. The crucible and the mold are thus brought into chamber 15 without being separated from each other at any time. The thickness of the key 29 is so selected that it is possible to close chamber 15 by lid 19 to make a tight fit over the mold-crucible assembly. In order to hold the mold and crucible tightly together, the supply of fluid to chamber 32' is cut off and that to chamber 25 is restored. The lid 28 is then closed.

The tube 10 is then rotated at a suitable speed by the machine motor. This speed was determined taking account of the cross-section of the bars and rings, so that the copper in fusion will be projected into the mold at the pressure necessary to obtain a cage perfectly free from blisters. This rotation also permits obtention of the solidification of the copper thus cast by suitably cooling the mold. For this purpose the walls of the chamber 15 are provided with apertures 10, as shown in Fig. 5, which is a section of tube 10 along line -5 of Fig. 1.

When the motor stops, the tube is brought into the vertical starting position. The lid 28 having been removed, the pressure on piston 16 is released and the lid 19 is removed. Then the pressure on piston 16 is restored so as to raise the crucible and its mold out of the hood 28 (Fig. 1). The mold is separated from the crucible, and pieces 4 and 5 are removed. There remains the rotor 1 and its squirrel cage, as shown in Fig. 6 along a longitudinal section of the said rotor passing through two diametrically opposed notches.

Fig. 7 is a separate view of the closed vessel formed by the crucible and the mold when the tube 10 has completed a quarter of its first revolution. The copper, flowing into the notches and the parts of the rings located at this moment at the bottom of rotor 1, forces air before it through the other notches and ring parts which for the time being are empty. This copper and air are thus put into movement in the same direction, the air passing progressively into the crucible at the same time as the copper flows out. Under these conditions there is no inclusion of air in the cast copper.

Substantially the same advantage would be obtained by operating the casting simply by inversion, with or without vibration. This latter modus operandi may be used in the case of aluminum. With the mold and crucible held together by any suitable mechanism, the assembly would then be simply inverted by a suitable handling mechanism and would rest by means of piece 5 on a horizontal plane before separation of the mold and crucible.

By the expression metal as used herein and in the 4 appended claims I mean to include both metals per se and metallic alloys.

I claim:

1. In a rotary casting apparatus having a frame, a rotary member having a shaft journalled in bearings in said frame, a crucible and a mold connected to said rotary member eccentrically of its axis of rotation, a housing completely enclosing said frame and said rotary member, and motor means for rotating said rotary member; the invention which comprises heating means positioned externally of said housing adjacent an opening therein, and means for moving said crucible and said mold radially with respect to the axis of rotation of said rotary member through the opening in said housing when said rotary member is at rest to a position adjacent said heating means for melting metal within said crucible which is to be cast in said mold.

2. Rotary casting apparatus as defined in claim 1 wherein said heating means comprises an electric induction heating coil arranged to axially receive said mold and said crucible.

3. Apparatus as defined in claim 1 wherein said crucible and said mold are removably connected to form a closed vessel, the chambers of said crucible and said mold being in communication through a plurality of passageways in such a way that molten metal flowing through one such passageway from said crucible into said mold displaces the atmosphere of the mold ahead of it through another such passageway and into said crucible.

4. Apparatus as defined in claim 1 wherein said means for moving said mold and said crucible radially of said rotary member comprises hydraulic means.

5. Apparatus as defined in claim 4 wherein the shaft of said rotary member is horizontal and wherein said rotary member further comprises a tubular container positioned in a vertical plane, said hydraulic means for moving said mold and crucible radially of said rotary member comprising a mold-supporting shaft longitudinally movable within said tubular container, said crucible and said mold being connected as a unit to one end of said mold supporting shaft, a piston secured to said moldsupporting shaft intermediate its ends, said tubular member having spaced transverse walls therein on either side of said piston to form a hydraulic cylinder therefor and conduit means in communication with said cylinder on either side of said piston for admitting fluid thereto to adjust the longitudinal displacement of said mold-supporting shaft.

6. Apparatus as defined in claim 5 wherein said mold and said crucible are completely received in said tubular container when said rotary member is rotated by said motor means.

7. Apparatus as defined in claim 6 wherein that portion of the wall of said tubular container adapted to receive said crucible and said mold contains apertures for the passage of cooling fluid to cool the molten metal in said mold upon rotation of said rotary member.

References Cited in the file of this patent UNITED STATES PATENTS 1,513,747 De Lavaud Nov. 4, 1924 1,844,701 Tama Feb. 9, 1932 2,009,489 Fritzsche July 30, 1935 2,065,213 Dolan Dec. 22, 1936 2,112,110 Marvin Mar. 22, 1938 2,304,067 Anderson Dec. 8, 1942 2,450,832 Kuhlman Oct. 5, 1948 2,636,232 Frei Apr. 28, 1953 2,696,647 Schutz Dec. 14, 1954 2,797,459 Meyers July 2, 1957 2,829,408 Shuck Apr. 8, 1958 

